FREE INSTITUTE OF SCIENCE 



MENDEL AND HIS LAW 



There are several important truths which have become pretty well established. 

 The first, and one of the most remarkable conclusions to which Weismann came, 

 was that an animal does not produce eggs. The animal grows from an egg. 

 While it is growing from an egg, all the eggs it is ever to lay are growing inside 

 of it, direct from the preceding egg. Accordingly, the egg is not produced by 

 the parent. Both parent and egg are produced from the preceding egg and 

 all the parent has to do with the egg is to fatten it up and send it out. This is 

 a very important fact, and if true, — and there seems little possible doubt of the 

 truth of it, — it becomes evident that the parent simply enshrouds, protects, and 

 nourishes and does not produce the eggs. Accordingly, what happens to an 

 animal during its lifetime can have no effect upon the quaHties of its offspring. 

 These are decided at the same time that the quaHties of the parent are decided, 

 so far at least as is decided by the determinants which are not thrown away. 

 This has given rise to Weismann's famous law that there is no heredity of ac- 

 quired characters. What that means is this : Suppose a horse to have had two 

 or three colts before it was discovered that the parent horse had splendid 

 trotting qualities. He is now put into training and transformed into a fast 

 trotting horse. Subsequent to this, he has several more colts. These last colts 

 have no more possibilities of being fast trotters than have those produced before 

 the horse ever thought of trotting. Indeed, these last have no more chance of 

 becoming trotters than if the quaHties of the parent had never been discovered 

 or exercised and he had plodded all his life in front of a plow to which he was 

 ill adapted. It is the fact that he has racing stuff in him and not that he is a 

 racer, which makes him the valuable sire of trotting horses. Of course, a 

 son may seem to resemble his father because he has learned to imitate his 

 habits, but this is a very different process. 



A second of the teachings made clear by Weismann is that we do not re- 

 ceive qualities from our parents, but the determinants of those qualities. If I 

 inherit from my father a house, he hands over to me the house which was his. 

 It is a very different process when I inherit the blue eye of my father. He 

 does not hand his over to me. He does not give me eyes at all. I receive from 

 the same egg he did one half of the same determinants, the other half of which 

 gave him blue eyes. The determinants, then, enable me to develop quaHties 

 Hke those of the parent. 



Another, at first sight almost startling, conclusion of Weismann's is that 

 we have two parents not because they are necessary to reproduction. This 



